Hydravent stops condensation under mattresses thereby preventing dampness and resulting mould and odour. It is a special material that consists of a spun polymer woven into a large open configuration that is bonded to a breathable fabric layer.

This light mesh of polymer does not compress, allowing an open layer of air to form. Cut to size, the fabric simply slips under your mattress. It is 17 mm thick, 1 metre wide and comes in uncut rolls 15m long or can be cut to length by the distributor.

Hydravent prevents dampness and the accompanying annoyances in three ways:
Allows warm air to circulate under the mattress, thereby minimising an essential condition for condensation.
The circulating air allowed by Hydravent promotes evaporation of moisture.
Hydravent separates the bedding from any moisture that might form.

The primary characteristics that contribute to the success of Hydravent include:
The semi-rigid structure elevates the mattress and bedding (even with a heavy sleeper) and does not compress.
Easy to cut with scissors
Easy to join in order to make any required width
Virtually maintenance free but can be washed
Very light weight (approx. 650 gm per square metre)
Outlasts the life of any mattress
Easy to roll up or bend through tight passageways

Hydravent Information For Customers
This information is meant to provide a better understanding of condensation and to provide information on Hydravent and its installation relative to use on boats and recreation vehicles (RV’s). While the two vehicles are quite different from each other they share the common problem of condensation – especially under mattresses. We are proud to say that Hydravent is the only product known to us that addresses the prevention of condensation beneath mattresses and cushions. Hydravent is durable and maintenance free.
The Material
Hydravent is a coarsely spun black nylon material that is heat fused to a smooth grey synthetic polymer backing. The material is manufactured in rolls 15 metres long, it is 1 metre wide and about 17mm thick. Along one edge of the roll the gray backing is extended about 75mm past the edge of the black nylon. The additional backing material along the edge can be used to bond one width of Hydravent to another by using any good adhesive; some people have used “Liquid Nails” for this purpose. The nylon is not coated, it does not absorb water and it does not break down under normal use. Hydravent can be washed with a hose if it is soiled and it dries quickly. Hydravent weighs about 650 grams per square metre and can be cut with a pair of large scissors.
The Problem Hydravent Solves – Condensation
Without getting lost in technical terms, condensation is the result of warm moist air meeting a cold surface or colder air. Warm air can hold more moisture than cold air so when warm moist air is cooled it can no longer hold as much water and condensation takes place. Good examples of condensation are when you breathe out into cold air – you see the fog condense. A glass of ice water drips condensation when the warm air next to it is cooled. Cold air covering a warm area of the ground or covering warm water will create fog. Condensation forms between a cold mattress support structure and a mattress that has been warmed by its occupant. Moist air is not necessarily the result of water in the bottom of a boat. A boat can have no water in the bilge at all and still have condensation. RV’s don’t even have a bilge. A prominent source of water vapor comes from the people in the boat or RV who are exhaling warm moist air. This same warm moist air will condense on anything cold such as glass and the metal frames of windows and hatches. Condensation is most noticeable on occupied vehicles in the morning after a night when many of the windows, vents, doors, and hatches have been closed and there has been very little air circulation.
How Hydravent Solves the Problem
Hydravent allows air to separate the cold mattress supporting structure from the bottom of the warm mattress. The air acts as insulation. Hydravent allows air to circulate under the mattress, moisture is carried away in vapour form and the cold supporting structure is warmed by the circulating air. Please understand that all of this information also applies to cushions, areas around ice boxes or refrigerators that sweat, etc.
Things to Keep in Mind
There is no magic available to get rid of condensation. There must be air circulation and ventilation or nothing will work to solve the problem. If a number of people occupy a boat or RV and all of the windows, doors and hatches are closed it will just be a matter of time before everything they touch will start to feel damp. How to get rid of condensation around window frames and hatches? Open them up a little, turn on a fan, get the air circulating. How to get rid of condensation under mattresses and cushions? Let air circulate beneath them with Hydravent. The worst possible condensation condition occurs when a boat or RV has a water tank as an integral part of the structure and a mattress is placed on top of the tank. By morning the mattress user will find an enormous amount of water under the mattress and there will be a need to dry out all of the bedding and the top of the tank. A serious associated problem is the rot that can develop in adjacent structures as a result of the constant fresh water soakings. The second worst condensation condition occurs when a boat or RV has a built-in water tank and the mattress is placed on a supporting structure immediately above the tank. While the condensation may not be as severe as in the first situation above, there is bound to be serious condensation. Condensation under mattresses is such a common problem that many mattress manufacturers use a vinyl covering on the bottom of their mattresses in anticipation of the condition. This does not solve the problem; it just keeps the moisture from being absorbed by the mattress.

There are three basic mattress designs in common use today. The most expensive is the custom inner spring mattress. It is interesting to note that no popular mattress on the market today seems to be constructed to provide enough air circulation under and through it to alleviate the condensation problem. The other two mattress designs are similar in construction but use two very different foams for support. Latex rubber is the best foam, is the most comfortable and is the most expensive. It is“closed cell” foam so it does not absorb moisture. The bad news is that it does not breathe under the person on the bed. Most manufacturers build in a thin cotton mattress on top of the foam to take care of this problem. The most common mattresses are made from polyurethane foam that is “open cell” and will absorb moisture. It is difficult to dry out, it is made in various densities and it is the least expensive.

Other Solutions
Again, there are no magic condensation solutions. Here are a few ideas that can be used alone or in combination with varying degrees of success. Keep in mind, however, that condensation is not strictly a function of the climate, the temperature or in what part of the world the boat or RV happens to be. In San Diego – the mildest climate in the United States – some of the worst condensation examples have been seen. Condensation can occur in one area of a boat or RV and not in another. Typically the worst areas for condensation are in areas of water tanks and where ever there is poor air circulation such as the forward bunks in a boat. Wooden boat hulls seem to be less prone to condensation due to the insulating qualities of wood. Also remember that some of the alternative solutions can be active energy users. This is acceptable if the boat or RV is at a dock or campground and has outside power to run the equipment. The generator might need to be on more than usual if a boat or RV is cruising. There are practical considerations based on the size of the vehicle (boat or RV), the energy use, the equipment on board, whether the vehicle is in use or not, the number of people on board, etc. A more passive approach would be to open as many doors, windows, vents, etc. as possible during the day. A vehicle left for any length of time should be left with drawers, doors and cabinets open. A rule of thumb is that the larger the bodies on the mattress and the longer they stay there the more condensation there will be. There is no other way to say it. If, for example, it has been raining for days and the people in the vehicle are spending more time on their beds reading during the day then there is apt to be more condensation under their bunks.
Other Uses

Any scraps that might be left over from cutting Hydravent can be used for numerous other valuable related purposes. It works great under cushions, under sail bags, in the bottom of lockers, under cans to prevent rust rings on the bottom of cupboards, under Propane tanks or outboard motor fuel tanks, around bilge pumps to keep trash out of the pumps, and around iceboxes or refrigerators that sweat on adjacent upholstery or wood.

The black nylon is the bottom and is placed next to the supporting structure. The gray backing of Hydravent is the top. The mattress and/or cushion goes on top of the grey backing. Cutting to fit can be done with ordinary scissors but large scissors are better. Intricate mattress shapes may need a paper template, otherwise just laying the Hydravent on the bunk and cutting in-place works fine. You can also use your existing mattress as a template. As mentioned before, you will notice a 3” flap of gray material along one edge of the Hydravent; that is for joining two pieces. Lay down the pieces to be joined together, spread an adhesive such as Liquid Nails on the flap and proceed according to the instructions with the adhesive.

Sheets and blankets should be tucked in under the mattress and above the grey backing. Hydravent should be extended beyond the edge of the mattress to the extent possible. If a mattress is against the side of a cold hull or wall then Hydravent should be extended up the side of the hull or wall just past the top of the mattress. The installation is simple. There really does not need to be an instruction sheet, there is no owner’s manual, there are no moving parts and no maintenance is required.

Cleaning, if ever necessary, is best done with a hose while the material is spread out on a deck or dock. Avoid high pressure spraying, especially on the black nylon side, in order to keep the gray backing from delaminating from the black nylon. Swishing Hydravent around in a tub with household cleaners works or putting it in the shower is okay too.

Hydravent will keep your bedding dry even if there is some condensation under your mattresses or cushions but that is not total success in our opinion. If moisture forms beneath Hydravent it simply means that there is not enough air circulation and more ventilation is needed. Open some window and/or vents, get some air moving and make sure you have tucked your bedding under the mattress and above the gray part of the Hydravent. Consider what may be making your mattress supporting structure so cold and insulate the area directly beneath the supporting structure.
Keep in Touch

We are proud of Hydravent and its ability to solve condensation problems for thousands of customers all over the world. If you have any questions or suggestions please call, email or write to us. We want to hear from you!